1. Field of the Invention
This invention relates to subscriber loop systems and, more particularly, to a bridge lifter circuit with tip party indication for use in such systems.
2. Description of the Prior Art
Where two-party telephone service is used with subscriber loop carrier systems, the two parties, known as the tip party and the ring party, are often required to share a common channel from the central office terminal (COT) to the remote terminal (RT) of the subscriber loop carrier system, thus necessitating at least two different types of channel units at the carrier terminals: one type for single-party service and another, more expensive type, for two-party service.
Furthermore, in some applications, bridge lifters are located either at the RT or at a field location between the RT and the telephones. Bridge lifters are used to isolate idle loops bridged on the line so as to prevent undesirable loading on the active loop and thereby cause unacceptable transmission loss. Remotely located bridge lifters create special administrative problems because, on the one hand, use of subscriber loop carrier systems require a group of subscribes to be closely located to the RT; on the other hand, two subscribers sharing a party line should be geographically separated to insure privacy in telecommunications.
Additionally, the telephones of at least one of the parties must be rewired to permit identification for selective ringing and billing purposes. When the two-party service is upgraded to single-party service, the telephones must be rewired. Thus, the administrative activity attendant with the provision of two-party service in conjunction with the use of subscriber loop carrier systems creates an economic burden which should be alleviated to make the service viable.